Question

How do scientists estimate the number of stars in the universe?

Answer 1

We have around $125$ billion galaxies in the universe. It is obvious that the scientists cannot count the number of stars in each galaxy, it will be practically impossible to do so. Therefore, the scientists make an estimation about the number of stars in a galaxy and use it to find the total number of stars in the universe.

Complete answer:
The universe consists of everything present in space. It is not easy to calculate the number of stars in the universe, scientists need to make a lot of approximations while doing this task. A universe consists of many galaxies in it. To make an estimation about the number of stars in the universe first an estimate has to be made for the average number of stars in a particular galaxy in the universe and then that number is multiplied by the number of total galaxies to get the total number of stars in the universe. The galaxies may contain billions of stars in it and the universe contains millions of galaxies in it. All this cannot be done just by counting each star with the use of a telescope as there are millions of stars in the universe and most of them are not even luminous enough to be visible. The estimate about the number of stars is also made by the satellites that are sent in space.

Note: This is not the only method used by scientists to estimate the number of stars in the universe. They are coming up with many new methods to make their work easier. By the use of satellites this work has been made a lot easier. Scientists have estimated that there are around $100$ billion stars in a galaxy and around $1$ billion trillion stars in the whole universe.